This is garlicbunny's hubby (of 32+ years). Thank you ladies for the words of wisdom....especially the Mares RULE! Geldings drool! comment...
First, I would like to say welcome to the forum. There's a lot one can learn on here but remember that there are a lot of just opinions too.
I'm glad you did join because there does seem to be more females than us guys.
I don't know if you had thought of it, but before you buy either horse, it would be a good idea to have a vet check it over first. They can check for things that could be a problem. The mare may be older but you could have a lot of years left to ride her if she's healthy. The gelding may be younger, but you'd have to put so time into him to get him like the mare.
Eventhough the gelding may look nice, other things like personality, attitude, and functionality should be considered too. A sports car can look nice and handle great, but it wouldn't do well hauling horses around. A big truck may look good and can haul things but doesn't get good fuel mileage or parallel park real easy.
Maybe in the end you'll click better with the gelding. I like either gender, but I can usually "click" easier with a mare, not all of them though.
I hope it works out well for you.