As some have mentioned already, it depends on what you want/need. Different people have different criteria for size/form factor, cost, amount of light, type of battery, carry options, etc.
For me, my only real "EDC" is my KeyMate on my keychain as it's the ONLY light I carry Every Day.
My personal carry lights are either a V2 or a Nuwai Q3. I don't mind carrying them on my belt in a holster at work and they fit well in my pockets (I prefer to wear cargo-type pants with more pockets), but you may differ and want something sleek and very small. I like 1-cell lights with a somewhat thick, short body, but that's a personal preference. I don't mind having to run CR123A or R123A batteries, but you may want AA/AAA cell types. Both my V2 and Q3 offer enough light and throw to be used outdoors and can run off recharables or primaries(tho, the V2 doesn't run off primaries very well). I plan on picking up a Jet1 also to rotate as a personal carry light and it offers the ability for various cells (alkaline AA, NiMH AA, Li AA, CR123A, R123A).
Ideally, I'd like either a McLux PD or Jil Intelli for the quality and multi-level output. However, none of the lights I own are currently more than $40 (tho, the planned Jet1 purchase and possibly a Jil DD will push that to $70). I can't justify to myself, along with all the other expenses I currently have, for a light of that cost. If I could afford it tho, either one of those would be my ideal. I'd likely lean toward the Jil due to the smaller form factor and lower price (I'd feel really bad losing a PD).
For the time being, I'll just modify my Q3 with a 2-stage switch and have a much lower-priced, 2-stage light that has enough output and throw for outdoors use (something I think is important for a personal carry light as you don't know where you'll be when you need it). I have other lights I really like such as my TM-313X that make a good amount of light for indoors use and has good throw for indoors, but it's not very useful outside of the house...same is true for the new X1, I wouldn't mind picking it up for $20 (not yet at my local targets), but I wouldn't use it for my personal carry light, more as an indoors light.