Depends what you are cooking.

Titanium is thin and has terrible heat diffusion, but stainless steel isn't much better. Doesn't matter if you are boiling or heating only liquids, But if you need better heat distribution, thicker aluminum pan with non-stick coating inside will be both lighter and easier to cook with. Try to avoid "teflon" non-stick (gives off toxic fumes at high heat, and less durable) and find one of the newer non-stick materials which I think are akin to a ceramic coating. If having a separate shallow fry pan along with a pot, make sure they nest for compactness, usually the fry pan over the pot base.

I still have my trusty stainless 2 or 1.5 liter pot (can't recall) with "stepped" lid that fits several of their pot sizes and the frypan. I think the pot is 2L because I needed that size to hold inside, the folded stove (MSR Whisperlite International (multifuel)), repair kit, fuel pump, and the folding fiberglass fabric cover from an Outback Oven, which improves the heating efficiency on the pot, without the huge space taken up by the corrugated metal MSR heat exchanger.