I started with a H&R 20 ga. break open which was great for rabbit and squirrels. It was stolen from me years ago. My next was, and still is, a Mossberg 590. I love my 590, very simple disassembly for cleaning and never a problem of any sort after THOUSANDS of rounds, but,,, if you get one you'd better love the barrel that it comes with because that is what you've got.
For a new shooter I would recommend a Remington 870 or a Mossberg 500. Both are available with a field / defense barrel combo and have many, many aftermarket barrel and accessory optons making them both not perfect for but suitable for any purpose. The only advantage the 500 has is that is has passed the 3443 MIL-SPEC standards for reliability and functionality but this isn't as important to some as to others.
I feel that 12 ga. is the most versatile but some shooters of smaller stature are better served by a 20 ga.. The felt recoil is lower vs. the power you get, I think it is 75% of the power of a 12 ga. and 66% of the recoil when comparing full power rounds, but I could be wrong. The length of pull is shorter as well as the distance to the forend, which helps correctly fit the weapon to these shooters and prevents over balancing resulting from compenstating for bad shooting stance.