Here's my opinion based on what I have owned and used so far in the midrange detector area... PLUS if you enjoy detecting as much as I have in my first year, where to go from your first detector...
This is just my personal experience and opinion. Depends where and what detecting for also, you know?
My hunting is in western PA in local parks, state parks, old home sites, back yards, around old churches, old mining sites, some fields...
MINELAB X-TERRA 705 : my first detector. more accurate TDI than some of the lower end machines, good depth. some options to learn, but not frustrating. very light. Sold it and upgraded to the E-TRAC. Wish I would have put the 18.75 MHZ coil on it and used it as a back-up gold hunting machine.
FISHER F2 : my spare detector. Runs pretty even with the Garrett 250 which I saw someone use. F2 has the number display which the Garrett 250 didn't. Easy to use, which is great for a loaner for a noobie, but no real options for site criteria to fine tune. Great bang-for-a-buck.
GARRETT AT-PRO : great mid-range detector that is weather-proof. lot of initial problems when it came out like no cam locks, falsing when shaken, etc., but Garrett fixed many by 2012. I'd definately consider for a first detector, or for a back-up for a high end detector when the weather sucks and you still want to go out but not take the chance frying your E-Trac, F75 LTD, V3i, etc...
WHITE'S M6 : First detector I ever saw someone use and was showed how it works, at a park last year. People that have them, including the guy I saw, love the M6. Mid-range detector. At that time, I was pretty amazed at how it found some coins, and thinking back now, it seemed simple yet powerful. The MXT-PRO would be similar but even better!
TEKNETICS T2 : bought one off a friend who needed the money, used it a few times, and sold it. Why? Ran them head-to-head with my E-Trac. Decided to keep the E-Trac because of the time I put into it, which is bringing great results now. Any detector can be used 'out of the box'. If you have a little bit experience with detectors, know the basics, have 5 hours to learn the E-Trac and T2, you'll love the T2. Very light, easy to learn menus/fine tuning, and great depth on some coins I buried. I actually ran it very hot the few times I had it, yeah it was chatty, but MAN was it sensitive! At $200 cheaper than it's copy-cat Fisher, it's sweet power-for-price.
MINELAB SAFARI : Was out at a Pittsburgh park with a guy from another metal detecting site 'Safari John'. He had his Safari and I was using my Xterra 705. I loved how it separated good stuff from junk even better than my 705. He was experienced, BUT he explained 'how' he was using his Safari to do it, and I was impressed and saw how he was doing it compared to my 705. The is priced between the 705 and my E-Trac, but feature-wise, I think it falls perfectly between them too.
MINELAB E-TRAC : My main detector now. An amazing machine and you seem to love it more every time you use it because you learn more about it and how to take advantage of it's features. Tons of features and settings for different locations, treasures, etc. Takes time to learn how to maximize it, and people getting this detector and either #1 not taking the time to learn, or #2 want a turn and go will get frustrated or think the machine sucks, but it's more or less operator error or lack of operational knowledge. Costs about $1500 and I hope one day to meet up with someone with a V3i to check out both. If you are a computer geek, you'll love the USB port that connects to your computer to customize hunting programs for your personal locations and likes/dislikes.
..... well, that's my thoughts, and for a first detector in the mid-range $$, based on what I've used, saw. and researched (for my hunting locations), I'd get:
GARRETT: AT-PRO
MINELAB : X-Terra 705
WHITE'S : M6
FISHER : F70 (tuned down F75)
TEKNETICS : Gamma 600 DD
TESORO : DELEON (has the TID, which is great)