Just go down to the local mass merchant/hardware store and buy an inexpensive homeowner saw with a 16" bar. There is no point in spending a lot of money on a really good saw, as there is a better-than-fair chance you will damage it irreparably with your lack of experience. Furthermore, you may decide that you cannot tolerate the noise and the dirt and the risk of hurting something or yourself.
As with all new endeavors, buy better equipment when you have a better understanding of what you will be doing. If you are dead set on getting a better saw than the cheapo down at Home Depot, head over to the small engine dealer and check out the homeowner saws in Stihl, Husqvarna, Echo, Johnsered, or whatever brand they happen to sell. If you like the dealer, then you may be better off this way, 'cause most guys don't know how to fix a saw, either. Trust me! It will need repairs.
Study a bunch of YouTube videos, especially any that demonstrate how to avoid "kickback". I had a young fellow tell me he was an expert with a chainsaw, but he didn't follow my instructions, grabbed a different saw than I told him to take, and he was in the hospital that afternoon with a pretty horrible chop across his face with a running chainsaw.
Be careful, chainsaws can hurt you.
Battery saws are great if you happen to get one that complements your other battery-operated tools. I'm inclined to think that most folks will wear out the battery too quickly, and then the saw sits around for 6 months while the battery goes bad. Most of those big batteries cost more than a whole new gas-powered saw that will outperform it too. If you use them regularly but not all day long, they are probably well-suited for some folks.