Which lenses should I purchase? Zooms? Primes? A combination?

[Fast Glass]

For your intended purposes a zoom will work great, as David said you don

[Daniel Browning]

Generally, I like to encourage people to get primes (I shoot all primes myself). But in your case it seems like a zoom would be more useful. Group shots and landscapes are often f/5.6 or narrower, so you don

[ham]

For landscapes I'd definitely consider the 15-85mm. The extra angle of view makes it more appealing for landscapes IMO, I have one and my favourite shots with it have all been taken at the wide end.

[neuroanatomist]

+1 on the 17-55mm - IMO, it's the best general purpose zoom for a crop body. At the wide end, the 17-55mm has the least barrel distortion of the three (17-55mm, 15-85mm, 18-135mm). Sharpness is similar between 17-55mm and 15-85mm (both better than the 18-135mm), and the 17-55mm has a bit less chromatic aberration.


One combination that I found very useful when starting out was the 17-55mm plus the 85mm f/1.8 for portraits (the 85/1.8 is one of the best values in the Canon lineup in terms of IQ for price). That combo would keep you under $2K, and provide a versatile, functional kit for the types of shooting you like to do.


The Tamron 17-50mm non-VC is a decent lens, altough not quite as good at f/2.8 as the Canon 17-55mm (stopped down to f/4 and beyond, the Tamron is just about as sharp, although the CA at 17mm is pretty bad). For half the price, though, it comes quite close.