If you are replacing the faceplate you may as well get a filtered one. Checkout ADSLNation or Clarity webshops.
O2 LLU would almost certainly be an improvement over AOL but if you use the AOL software you'll need to adapt to using a browser maybe an email client instead.
Some swear by the DG834v3 and others swear about them. It uses a TI chipset unlike the other versions and I've seen some report that these are good but my own experience is that they were very poor performers on both my own and sons lines - it probably depends on the exchange equipment.
If you do swap to O2 and find their supplied kit lacking there is nothing stopping you from buying your own (the settings are non standard but documented on the web).
If you can't fix it with a hammer you've got an electrical problem.