Maybe take little pieces of paper write the name of each of the above put in a hat and pull one out ( joking aside ANY of the engines the guys mentioned are excellent) I have an SK, A Jen (same as SK) , OS46AX and an ST 40 all by the way are converted to diesels the ST 40 for $50 is the best value but as stated $20 more increase your choices, the OS AX46
does have the smoothest throttle response , its a 10 the rest 8-9 on a 1-10 scale really means nothing it is however the most bucks martin