Hi Max.
Your querry may start a riot in here.
In my experience, modern Tamiya kits are generally very good for detail and fit is excellent but I personally hate their decals. Not a big deal for me, lots of aftermarket markings out there and plenty in my stash as well. Tamiya only refers to their own paint line for colors and will give you mixing ratios to get the color that you need. Again, not a big deal. You just may be doing a little research to find another paint that will suit your needs if you don't want to get into mixing. This forum is a great place to find advice and opinions for paint options.
Really, it all comes down to the subject that you want to build. When it comes to auto kits, you may find their selection limited for American subjects, but if you want a JDM subject you will be spoiled for choice. Again, look at online reviews because Tamiya makes several "curbside" kits that will have no engines. I like building the engine, so sometimes the Tamiya kit doesn't suit me. For auto kits, I can suggest their Toyota Supra MK4, 300ZX, RX7 R1 or the Porsche 959. All are older kits so they are cost effective and are hard to beat.
Aircraft kits are a different story. I build primarily in 48 scale. The older kits that can be found cheaply like the Sea Harrier or the A-10 I found to be lacking. But if WWII subjects are your area of interest I have never regretted any of their kits and they have an excellent selection. I recently built their F4U Corsair and the Me 262 and have no complaints. I also enjoyed their F-16 and A-1 kits. Again, a little older so they were fairly cost effective. I don't know if I would spring for the new F-14 kit regardless of the praises people have bestowed upon it due to the cost alone.
Well, I hope this helps. I'm sure you will get alot of responses to your question. You picked a good spot to seek help.
Good luck!