I've owned almost every type of commercially available black rifle in Canada, some more times than others. I've had three different Tavors, one from each generation. I bought one of the first when they originally came into the country. For AR15s, I cannot even count the number. Some were bought new, some used, most I've built from the ground up.
As far as comparing the two platforms, both have positives and negatives. The Tavor works well, is very robust and it's as accurate as can be expected from a stock, service rifle. I'd say the AR system is more accurate, if I had to choose. This is likely due to the gas impingement as opposed to the piston operation. Ergonomics are OK for the Tavor, but I'm probably just more used to an AR layout from military service and years of shooting them. I will say, that with practice, one can overcome almost any differences between the two systems. The Tavor isn't light, but isn't super heavy either. The bullpup design carries its weight well. In general the AR is going to probably be lighter.
The quality of the Tavor, is good but not great, and if I were redesigning it, there are areas I'd change for sure. It's also quite tall and the height over bore is one of the tallest I've seen. It seems to me that there is a lot of wasted space and it could be made more efficient. The AR is definitely sleeker of the two. In my opinion, the best thing the Tavor has going for it is it's short, very maneuverable, overall length. It's footprint is about the size of a typical 10" barrelled AR. Pretty awesome when you've got a full size barrel in that small of a package. When it comes to real world use (personal protection), I wouldn't hesitate to carry a Tavor, but it wouldn't be my first choice. The AR would.