Thanks guys for the response. I think i'm looking for a wider aperture lens because i'm a bit frustrated when I cannot use wider than 5.6 aperture when I'm on tele side. Size and weight is not an issue I just think my 18-200 lacks on the wider aperture on the tele-side.
Not sure how I could answer this without facepalm-ing myself.... :sweat:
1st off... what is your desired max focus range ?? 55mm, 70mm, 105mm, 300mm
2nd... what is your desired max F-Stop ?? f2.8 or f4
All 4 lens you have listed is difference...
* 17-55mm on your 60D, becomes a general purpose lens of 27.2-88mm (in 35mm)
* 24-70mm & 24-105mm on your 60D, becomes a slightly narrower general purpose lens of 38.4-112/168mm (due to crop factor)
* 70-300mm on your 60D, becomes a telephoto lens of 112-480mm (due to crop factor)
So...
* How does having the 17-55mm solve your problem of ''cannot use wider than 5.6 aperture when I'm on tele side" when your lens reach 200mm and the 17-55mm could only reach 55mm ?? Same thing with both 24-70m and 24-105mm...
* 70-300mm at a range of 155-228mm has an aperture of f5.0... at 229-300mm, f5.6... which isn't too difference from your 18-200mm
Ok... here is the short answer
1) Get the 17-55mm if you are not going FF anytime soon and you don't mind have only a max range of 55mm (88mm)
2) Get 24-70mm or 24-105mm (depending which is more important to you.. f2.8 or f4) but you'll lose your Wide Angle of 28mm but gain in range (112mm or 168mm)
3) Get the 70-200mm f4 IS... or if you have the budget 70-200mm f2.8 IS MkII... both will give you a constant aperture of f4/f2.8 throughout the whole range of 70mm to 200mm