If you're only buying one, get the STW1011 IMHO; it's 3/8" drive which is easily reduced to 1/4" if you need and it covers the wider range of torque settings.
However if you have another wrench that overlaps the upper end of the STW1011's range, then I'd go for the STW101 - as it goes as low as 5Nm (rather than 7Nm) it'll be slightly more accurate at the bottom of it's scale.. e.g. cam cover bolts at 8Nm, which are right on the edge of the 1011's range.
For oil filter caps - if you mean the paper-element style Omega cap then you don't need any special filter wrench, just a large spanner to get it started (and then I use a smaller ratchet inside the 3/8" drive hole to spin it the rest of the way off). If you want to do other cars that use a canister filter where the whole can comes off, then this one works great;
http://www.justoffbase.co.uk/Oil-Filter-Claw-Wrench-43-102mm-Sealey-MS004