Long post, I warn people not to judge model kits by the manufacturer alone. Instead, look for the best (or skill appropriate) kit of a particular subject. In addition, companies have been reboxing other company's kits for decades. For instance, Tamiya makes an outstanding M4A3E8. The have also reboxed an awesome Tasca/Asuka M4A3E8. They have also reboxed Italeri's 1980s issue M109 and 1990s M109A6 Paladin. There are better versions of the howitzer available from other companies. So chosing Tamiya for one of the best Shermans is good, but not for the best M109. You gotta do some research.
The Tamiya Walker Bulldog is an ancient kit that was surpassed by both Skybow and AFV Club kits around 2001-02. It is still a great starter kit and is rather inexpensive. It looks like an M41 when done.
But if you want the best Abrams tank, be it a straight M1, M1A1, AIM, SEP, etc., you want to chose a company other than Tamiya. But if you are a novice modeler, the Tamiya kits are the easiest ones to build and will look good enough for the casual modeler.
If you want an M88A1, there is only one basic kit that was done by AFV Club and reboxed by Revell. So for that kit, you might want to get the best priced one since the model is the same inside.
As far as price goes, when a new company announces or releases a new tooled kit, older companies with the same or similar kit will quickly reissue their old kit in order to get unaware buyers to select their kit instead of the new kit because it is slightly cheaper. For instance, when Academy released a new M3 Grant and Lee series of kits, Tamiya reissued their really old and not very good kits. Buyers see the Tamiya name and grabbed the old kit off the shelf and left the newer better kit there.
Italeri has some good kits, but many of them are from the 1980s and have been surpassed by more recent versions. They also took over Esci's armor line and reissued these as their own. Some of Italeri's last new tooled modern US armor kits were the M1A1 and M1A2 kits from the mid 2000s that weren't as good as other company's kits.
As far as companies to avoid, there are some eastern European companies that rebox each others kits of obscure early WW2 subjects. They are interesting subjects, but the models are poor and the plastic brittle.
Even one of the current top of the line manufacturers, Trumpeter, started out with very poor motorized copies of Tamiya and Academy kits in the early 2000s. They currently have some of the better Soviet era tank kits, LAVs and other modern vehicles. Their Abrams series has been left in the dust so to speak.
Bottom line, if you are going to spend $40, $50 or more on a model kit, you need to whip out your smart phone and Google a review of said kit. Also look to see what the online price is before forking over bucks at the store.