You've received some good advice here so far, I will try to add to it.
Length, storage, livewells, overall condition, motor, trailer, etc...All need to be balanced against what you can spend.
In general, I'd say you want to lean heavy on length since you plan to fish the upper Bay. You don't want end up wishing you went bigger. When it comes to glass boats, generally a 20' boat can do everything an 18' boat can...But an 18' can't do everything a 20' can.
For used boats, motor and trailer condition need to be considered as extremely important too. If either turns out to suck you will regret everything. Get both checked by a professional. For motors, some have bad reputations (the FICHT is probably one of the more notorious ones) so avoid those...Even if you get a 'good one' the resale value will be hurt significantly.
Remember, the boat is just a tool to take you to the fish...So make sure you get one that matches your fishing goals!
Get your budget figured out, get your goals figured out, and then start looking. Narrow it down by brand once you start finding some that fit your goals. Look at as many as you can and keep an open mind...Whatever you do, don't fall in love with the first boat you look at! I've seen a few people do this and they ended up with something completely different that what they set out for, obviously regretting it.
Don't get too caught up in what electronics/extras are on the boat, but don't pass up a great deal either. If a boat is a little out of your price range but comes with $3,000 worth of electronics, a brand new quality trolling motor, or with all of the previous guys fishing gear, it could end up being a better deal in the long run.
After all that, if I were to rank the brands you listed...I'd put Stratos at the top (For obvious reasons haha)