I've been using rtorrent for years and I wouldn't ever suggest anything else. It's just so damn simple and reliable. I love the concept of watch directories too. Upload a torrent file to a specific directory, and the data will be downloaded to a specific directory. You can have multiple watch directories for different types of data.
I like Deluge, but I really wish its default API (protocol) wasn't so difficult to use. It's bencoded Python objects as far as I can tell. If you've never heard of bencoding, that's because it's only used by Deluge.
Pay for it then? Netflix scratches my entertainment itch now, but prior to it launching in Australia I almost went ahead and paid for uTorrent. It's a good, lightweight client. Software that works well deserves to be financially supported.
The parent comment was suggesting paying for uTorrent to remove the ads, not paying for Netflix. (Although paying for subscriptions to overseas services might also be an option.)
qBittorrent is just as good and free, why pay for something that's maybe a few MB smaller? Do you really not have gigabytes of RAM on your machine? If you don't, I suggest spending that money on RAM.