My vote would be for the Mini 30.
Ruger makes factory 20 round magazines for the Mini 30 now (maybe 30's too? Not sure...) It's really a great all around rifle.
I love the Marlin 30-30 as well. I have to be honest with myself though, and if I could only have one or the other it would be the Mini 30. Despite the higher cost of the Mini 30 and it's magazines, (and noting that additional magazines are not an option with the Marlin) the ammunition is less expensive, and I believe the rifle has a greater range of use due to the semi automatic action and removable magazines.
The Mini 30 can also be a better option than an AK-47 for the simple fact that it has better iron sights and no pistol grip. Whether you visually prefer the clean traditional lines of a rifle with no pistol grip, find it easier to fit into gun cases or store in general, prefer the feel of a traditional rifle hold, or whatever, sometimes it is preferable to something like an AK-47. Also the Mini 30 comes with steel scope rings for easily mounting a 1" tube scope. However I've found that with a scope mounted you can not remove the bolt for cleaning, but it is still easy to move the bolt around inside the receiver to get it clean from all angles without the need to remove it, so no big deal.
Getting back to the Marlin 336 30-30. It's a great rifle, I'd guess it to be a little bit better in accuracy than a Mini, whether it's because of an easier trigger pull or whatever, it just seams to be the case, but either rifle will be good enough for your uses, but I doubt that either of them would make great target rifles. The Marlin is also easy to mount a scope on, and it really is an enjoyable gun... nothing quite like the feeling of working the lever and sending a beautiful 30-30 cartridge into the chamber for your next shot.
I honestly think you'll be happy with either one, and they are both very capable rifles. But I'd give the edge to the Mini 30 for it's removable magazines, semi auto action, and less expensive ammo despite the rifle costing about twice as much.
Another note on ammo. I would never buy a 7.62x39 rifle if I didn't plan to shoot steel cased ammo out of it. I don't have a Mini 30, and if I did, I'd shoot nothing but steel cased ammo, and if I found it to be unreliable with such ammo, I'd be very sad, and probably sell it... I'm not going to shell out for brass cased factory 7.62x39, and I would prefer to stay away from the surplus brass cased corrosive ammo.
Let us know what you end up deciding on
WOOPS.... I just went up and read some of the previous posts and see that you DID buy the Mini. Congrats! That's the same model I would have gone for. Please let us know how you like it when you get the chance