For "everyday" tasks they are pretty comfortable.
They just aren't as nice as the wooden or rubberized handles when doing some hard cutting like wood carving, or breaking down a lot a lot of cardboard.
I have the Kershaw 1870, it's not perfect but it's
a good enough knife for me..
Lockbacks.Have the strongest lock but are the hardest to Open
Ex:brand new cold steel or a stiff, cheap lockback.
Linerlocks.Have the weakest lock but are the easiest to open if the liners dont have sharp edges.Take my opinion with a grain of salt because ive only handled the cheap linerlocks.
Framelocks.They can be pretty strong,and be quite slim depending on
which knife you get, opening them isn't very difficult but i've handled few that were a pain in the thumb to open.
These are my generalizations on the 3 locks...You might get to have a linerlock that feels like its strong but hard to open or a lockback that is really easy to open but feels like it would be easy to make the lock fail.
Knives come in many different shapes,sizes, colors,locks (if they fold) and prices.You should check out the knives that are out there before
deciding to buy one.Blade HQ made a video about the 3 locks you mentioned here on the forums a while ago...