"My concerns are depth,accuracy,reliability.Also does the screen display help a lot for newbies?Thanks again for any help".
For coin hunting, the machines mentioned have sufficient depth capability for most of my hunting. Tot lots are fine also for coins, jewelery etc. For relic, I go with other machines not mentioned, although it's not to say the ones mentioned will not get relics within their capability. Nuggets - I go with other machines, preferably a gold detector.
Accuracy - not all sure by what is meant by that one.
Reliability - I have had no issues with Tesoro's or the 250 - and Tesoro has great warranty/repair.
Bottom line - I see nothing wrong going with a Tesoro as they are good machines, and nothing wrong with the 250 if you prefer a display. They are all popular and will provide some good hunting.
Although I have a handful of machines, and some costing over a grand each, I often grab my lowest cost detector, the Compadre, and have loads of fun with it. When I take along folks who don't have a machine, they most often choose the 250, probably for the display. It's easier for them to determine the coins.
If you have a local detecting club, and/or local dealer, you can get some hands-on.