Out of all the grinds, I'd have to say that flat grinds are definitely the easiest to do.
I started out doing convex grinds and they're a lot harder than most people would expect. It seems simple enough, just round the bevel over and whammo, but doing them correctly actually take a TON of practice and some serious talent. One of the most important things about convex grinds is getting the thickness and taper right. You really have to get those grinds as thin as you can. Then you've got the plunge and the line on the top of the bevel to worry about. You have to be careful to leave all the steel at the spine and if you vary your stance or get heavy handed anywhere in your grind (which is very common and easy to do) your lines will come out wrong and you'll really have to work at it to bring them back. Plus, all of the stuff I'm talking about is from experience using a KMG, so using anything less than that, it's even harder to get everything right.
Hollow grinds are somewhere in the middle as far as ease goes. Once you get your bevels started, it's really just a matter of watching your pressure and keeping you plunge clean. The big issue that you run into with hollow grinds is having the correct wheels to do them. I know that you can get away with using the wrong wheel for the job, Ian Van Reenen proved that to me, but you've got to be a salty dog to pull it off. I had Ian make a knife for me that would have required a 14" wheel and he managed to pull it off with, if I remember correctly, a 10" wheel. Ian is really great at grinding by eye so he did a great job, but any maker with less experience would have had a seriously tough time. As long as you have the right wheels for the size grinds you're doing, it's just a matter of practice and actually comes relatively quickly.
Flat grinds are something I wish that I had tried in the very beginning. Although, they might have spoiled me. I never even bothered to try one out until recently, because I was so determined to learn and become proficient with convex grinds. It was just a few weeks ago, I threw the platen on the KMG just to see how easy it was. I seriously stood there for a minute when I was done and thought, "AH HA! Now I know why everyone does flat grinds!" I'm not saying it doesn't take any skill or practice, and I realize that this is coming from someone who had prior experience with other grinds, but still, I was amazed at how quick and easy it was. Now I'm not trying to take the wind out of the maker's sails that do flat grinds. I don't want you to think that every maker out there who does them does "easy work" Most of the guys that do them well have put a lot of time into PERFECTING the flat grind and there's a lot more talent that goes into it than would be immediately evident. For example, choosing the angles at which they grind their bevels and maintaining those angles, doing a correct plunge, choosing the correct point to sharpen, proper steel selection and heat treat, etc., but as far as a grind that I believe will come quicker to the beginner, I think flat grinds would be the best to start with if you want good ego boosting results in less time.
Something to keep in mind is that I am one person and all of this is just my opinion. Plus, I'm still a new maker myself. I ground my first knife a little over a year ago and I'm still learning and adjusting. Hell, I might be giving the worst advice in the world. One thing I would recommend doing right off the bat is trying the different grinds and seeing which one you think you want to do. Do several blades with each grind. Then, get some feedback. All of the makers on here are super cool guys and are willing to help out newbies like us. Take pointers from them and get plenty of grinder time in.
As far as your equipment, as someone else already said, if you have the dough to go ahead and snatch up a good 2x72 grinder, do it. I wasted a lot of time working with smaller machines I had the money for. It wasn't until I got my KMG that I really started to see things come together. Having the right grinder makes all the difference in the learning process.
Have fun and happy grinding brother!
