Which is better for an older TV without HDMI?

The GPX DH300B. It has composite video and coaxial audio outputs, so it connects to older sets and receivers. The Sony is HDMI only.

Does either player play Blu-ray discs?

No. Both are DVD players. For Blu-ray you need a different model.

Which has better picture quality?

The Sony. It upscales DVDs to 1080p over HDMI and owners consistently praise its picture. The GPX lists 1080p output but has little owner feedback.

Can I play movies from a USB stick?

Only on the Sony DVP-SR760H, which has a USB port. The GPX DH300B has no USB input.

Is the Sony worth stepping up to?

Yes for most shoppers. USB playback, upscaling and a stronger owner reputation make it the safer pick for a main TV.

The Sony has the better-reported build and smoother tray mechanism. The GPX is a basic unit with fewer long-term owner reports.

Sony DVP-SR760H DVD Player vs GPX DH300B DVD Player

Buy the Sony DVP-SR760H for a living-room DVD player. It adds a USB port, upscales to 1080p over HDMI, and owners consistently praise its picture, sound and smooth playback. The GPX DH300B is a basic front-tray player with HDMI plus composite and coaxial outputs, but it lacks USB and has a narrower disc-format list. Neither is a Blu-ray player, so if you want HD discs, look elsewhere.

Choose the Sony DVP-SR760H if you want USB playback, 1080p upscaling and the better-reviewed build for a main TV.
Choose the GPX DH300B if you need composite and coaxial outputs for an older TV or soundbar and only play standard DVDs and CDs.

Prices

Sony DVP-SR760H DVD Player: $26.59 at eBay (last seen Nov 9)
GPX DH300B DVD Player: $45.00 at The Home Depot (checked today)
Difference: the Sony DVP-SR760H DVD Player is $18.41 cheaper than the GPX DH300B DVD Player at the latest prices (Nov 9 and Nov 11)