I have both a Sony (DVP-NS999ES) and an Arcam (DV-87). From a purely video-centric point of view, they both have advantages and disadvantages.
Sony Advantages
- provides best picture I've seen for videotape-sourced DVDs
- all kinds of options to tailor video output, probably more than anyone needs
- does not exhibit chroma bug (this only matters if you're sensitive to it)
- front panel display can be turned off
- has more bells and whistles than most people will ever use
Sony Disadvantages
- US model will not play anything but Region 1 NTSC discs
- picture not quite as "filmlike" with film-sourced DVDs
- has more bells and whistles than most people will ever use
Arcam Advantages
- provides the best picture I've seen for film-based DVDs, very cinematic
- plays PAL discs, even on an NTSC-only television
- can change regions or make region-free from the remote, no hacks or hardware changes necessary
- very simple menu structure
Arcam Disadvantages
- the remote control is very poorly laid out
- exhibits chroma bug; however, the effect is very mild and is less noticeable than most other players with the bug
- front panel display is bright and cannot be turned off
- very simple menu structure means not much fine-tuning control (although I don't think the player needs it)
From a sonics standpoint, the Sony plays SACDs and the Arcam doesn't. This may or may not matter to you. The Sony decodes DD and DTS, and can output decoded DVD-Vs through its 5.1 analog outs (with bass and speaker management). So, for someone with a pre/pro or receiver that doesn't decode DD or DTS but can accept a 5.1 analog output, this is the player. The Arcam decodes DD and DTS, but does not have 5.1 analog outs. The Arcam sounds substantially better than the Sony via two-channel analog outs. Arcam sounds marginally better on DVD-Vs through the coax digital out than the Sony. Arcam is substantially better on CDs, both via analog and digital outs. Arcam decodes HDCD.
Note - this is the cheapest Arcam DVD player. The more expensive ones are even better.