Keep in mind, the learning curves are different with manual and TTL.  Not a bad idea to have the options of both...that is what I do and mostly go TTL with tweeks to flash power.

With strobes( studio sorts, not camera based flash gun) I use a hand held meter to read the flash and then set and test.

I cannot recommend a particular camera flashgun since what I know on that is Nikon.   Best wishes! A good camera flash gun is well worth having.