You didn't say exactly what you use the gun for, but a Marlin 60 isn't a target rifle, so I'm guessing plinking and/or small game hunting.
I often see suggestions 40mm scopes, and while many people may like them, I feel like those are a bit bulky for lightweight .22 rifle unless varmint shooting or serious target shooting are in order. I like sticking to a 32 or 35mm objective. I also find the 2-7x range to be more practical for my purposes than a 3-9x or 4-12x as I have more use for 2x on the low end than 9x or 12x on the high end. I like the simplicity of a fixed 4x, but on one occasion, I missed some racoons because the field of view was too narrow for me to find them in the dark as they ran off. If I'd had a variable scope set at 2x, I am confident I could have stayed on them.
The AO scopes can be nice, but they also tend to have more bulk than regular scopes. I had a Burris 4.5-14 AO scope on one of my 10/22s, and I swapped it out for a smaller, simpler Burris Droptine 2-7x35 instead, and I have never regretted the switch.
I don't like to recommend people go over their budget (I myself don't have a lot of extra money to throw away), but I think you'll find that you'll get into another level of quality when you get up around $130-$150. Burris, Vortex, Weaver, Nikon, Leupold, and probably some I'm forgetting all have models in this ballpark. Not only will you see an improvement in optical quality (brightness and clarity are often more useful than higher magnification), but these are generally built as tough as centerfire models and simply have a different parallax setting. It often ends up being cheaper buying the scope you really want once than to settle for something less and then buy the better scope later on anyway.
If you really prefer staying below $100, I've liked several Simmons scopes that I've had.