Not telling you which way to go on this decision, all I can do is tell you my experiences in this hobby from the beginning.
Started with a broken BH unit for 3 months then I got a high tone Vaq with my tax refund and that is when my hobby really started for me.
Loved that thing and used it for several hundred hours and found plenty even though my soil is...rough.
Several months later I bought an F2 just to take on vacation and to give to guests, a little while after that I also picked up a vintage 7" coil Compadre because back then I was a died in the wool jewelry hunter.
I spent a lot of time getting to know the Compadre but I knew a lot already thanks to time spent with my Vaq.
As I spent time learning to hunt with the F2 something happened that surprised me...I really started to love this thing, a lot.
I found it was a blast to use and I was finding some great targets all through the initial learning process and then even more as I got good with it.
I still took out the Vaq and the Compadre too from time to time, I really do like the ability to switch between the two different types anytime I want and still do, but used the F2 more.
I moved to another state and continued to rotate all 3 units in the much better and almost perfect soil in my new home but still took out the F2 more often.
The behavior of all three in that environment was different...better, deeper and more solid signals at all depths.
I continued to learn and understand all of them but found that using the screen unit in the trashy park sites I usually targeted got me more good targets overall, percentage wise, as a matter of fact I won so many contests at my club meetings that several other members went out and bought F2's for themselves even though they all owned and hunted with much more expensive detectors too.
I won the most coins dug contest just about every month beating out the second place winner usually by hundreds of coins, first place in best jewelry as often as I was allowed to win by the rules and more.
Some say that those that use screens miss so much because screens lie, I guess there are some that believe everything screens say 100% and make all digging decisions based on that, I believe the truth is probably most of us are more like me.
Thanks to my training using Tesoros I listen to the sound just as much as I watch the screen and take ALL information I receive, filter it down in my head using my experience and make digging decisions on that...a much more logical way to approach this.
I have no X Ray vision, strange and weird things can an do happen out there so everything I see and hear I take with a grain of salt...all of it.
Over the last few years I have had a change in attitude about what I decide to dig.
In the beginning I used to be more of a dig it all type of hunter, even if I thought targets were trash you really never know so I dug most everything except iron for a long time using both types of detectors.
As time went on I found I just didn't have the patience, energy reserves or time to hunt like I used to so I looked for ways to cut down my trash digging while still keeping the percentages as high as possible of digging the good stuff and I have succeeded to a higher level than I would have dreamed possible.
I think I have cut out about 80% of the trash targets I used to dig using Tesoros, a little bit more when I use my Fishers.
Sure, I probably miss a few things here and there but I don't care because my volume total stays high, my bucket list items continue to be checked off one by one and I am a much more rested hunter.
In 2014 I upgraded by buying an F70 and started learning that one, soon enough I realized I was living at a deeper level with this thing and the screen information held even more useful indicators and clues as I learned to understand what I was seeing along with still listening to the tones.
Eventually I moved back to the south and that bad soil, I almost cried because I now had experience with both heaven and hell and I considered buying a PI unit because I knew from experience depth would be severely limited with a VLF unit and I was correct, and where I live I also have all the normal mineralization problems but also add to that an unusual amount of iron in my local sites made things even more difficult but by then I had that F70 so I hoped all the extra power and possible settings would help.
I hunted here using both Tesoros and the newer F70 and even though I was even better with all of them than I used to be when I lived here before the things I could do with the F70 far outpaced what could accomplish with my Tesoros.
Now I hunt with that one 98% of the time so you have to take that into account, and I had to learn a whole new language and set of behaviors and indicators too, but using the Fisher I have been able to get deeper than ever before and ID possible and good targets deeper than I ever had in the past using any detector.
Also masking is a huge problem here even on some more shallow targets.
I have been able to pluck out some great things with my Tesoros, especially my Compadre which I use more, but the amount and frequency does not come close to what I can do with the Fisher.
The reason...I believe it has to do with the screen and the extra and added information I get that helps me make digging decisions.
Others using Tesoros might be able to do better than me in my hunting environment if they had more skills than I do, of that I can never be sure, but I am no slouch with way, way over 1000 hours experience using both kinds and I have also used both types at many different sites like extreme trash, extreme iron, heavy mineralization and great soil where depth can be phenomenal.
Again, I am just talking about me here and nobody else, but I have been way more successful using screens because I am all about logic, commonsl sense, anally learning my tools to the utmost degree and using all the information received to make digging decisions.
It's all math to me, screen units give me both tonal AND visual information, more information I can observe, digest and possibly use than just aural info alone.
I still own and use my Tesoros, like I said not being able to use both kinds when I choose to would make me sad and frustrated, but when the chips are down and the site or conditions are difficult I am going to grab my Fisher because so far I have not come across any site or conditions it could not conquer because of the amount if information it supplies me.
If you can only own one I would not want to be in your shoes, I would urge you to keep a Tesoro and a capable screen unit in the arsenal at all times if at all possible.
If that is not possible then try a screen unit because like me you might be shocked and surprised on the difference and what you may get be able to do.
I personally can't speak for ID units but more times than not I hear the users of ID units say that they make their final decision to dig by audio sounds.? Strictly audio units along with visual units can miss targets at times if you don't investigate with digging!