Hengar's have very low guts regain, 75 at highest. This should be taken into account when choosing your Hengar's techs. Because of the low guts regain, i recommend selecting techs that have a high hit, as to avoid wasitng guts on a tech that is less likely to connect. Also take into account whether you want an intelligence or power based Hengar. Hengars can easily go either way.

I recommend the following:

Force Bomber, maxxed out this tech has 25 damage, 25 guts down, 10 critical, and 57 hit. Best of all, it only costs 28 guts. While the critical is low, the other aspects of Force Bomber more than make up for it.

Giga Shooter, 21 damage, 47 guts down, 5 critical, and 65 hit when maxxed. This is a great tech in my eyes. It isn't a heavy hitter, but the guts down is great, and it is almost sure to hit. Giga Shooter does cost 35 guts, but the fact that it rarely misses, makes it worthwhile. The down side to this tech, is that you need the aqua orb to get it, and orbs are no fun to get.

Remote Punch, If you have a power based Hengar, this is a good tech. At max the tech has 27 damage, 3 guts down, 4 critical, and 57 hit. Now this doesn't look too impressive at first glance, but Remote Punch can work wonders. The secret to this tech's usefulness is that in costs a mere 21 guts.

Core Attack, This is what I call a good BLS tech. Only costing 18 guts, Core Atteck has 22 damage, 5 guts down, 3 critical, and 52 hit when maxxed. Another benifit of the tech is that it is able to cause the Dizzy
effect.

Now, if you are willing to take a little risk, you might try these techs:

Ion Cannon, This is one powerful tech! at it's max it has 62 damage, 33 guts down, 17 critical, and 45 hit. This of course comes at a price, 50 guts. I warn you, while Ion Cannon is an amazing tech. You must remember that it will take Hengar longer than most monsters to regain the 50 guts lost from using this tech. Not to mention that with 45 hit, the tech will have quite a few misses, meaning 50 guts down the drain.

Giga Blade, This a tech most people would dismiss as having too low of a hit % (36) to be effective, or just too risky for their style. However, this risk is a well made one, as at 30 guts, you aren't investing that much for a tech that does more damage than some 50 gut techs would do. Hengar's Radar also makes it a bit more accurate than advertised. When maxxed, Giga Blade has 53 damage, even a bit of guts down (12), and 15 crit to make it even meaner every now and then. "He who dares, wins," -SAS motto
Giga Blade by DeadBuffalo

The techs that weren't mentioned here are not neccissarily bad, they simple do not measure up to the five techs I did mention. If you are simply raising a monster for in-game battles only, nearly any tech will do fine. However, if you are raising a competitive monster to compete with other skilled ranchers, the techs I have suggested just might give your monster the advantage.