Background - Im Emerald in Oneworld as EXP with AA and Gold on BA; Im top level in Skyteam as a Platinum w Delta

Network -- For me, OW has a very well balanced network which is important since I do several RTWs a year - the only hole is between the Middle East and SE Asia (SIN or BKK). Pre August - I liked transiting in LHR but the new one piece rule even for F pax make it less advantageous as I dont like to check bags

Lounges -- I find the general lounges by the Oneworld carriers I use (CX, BA, IB, AA, QF) very good and superior to what I have seen on an overall basis from other carriers - I base this on showers at intercontinental hubs and availability of food as well as comfortable environment and sufficient seating. I think an advantage of OW is at the top level I get to access F lounges (w Skyteam this is not the case and I have a colleague who is 1k on UA but I think with SQ and TG he only gets the J lounge) with the exception of Concorde Room in LHR and JFK.

Credit of Earned Mileage -- So far I have not had any major problems and credits come fairly quickly.

Class of Service Offered - OW still has the ability to put together F RTW itineraries fairly easily and this will improve w JL whereas Skyteam this is almot not possible anymore now that AF has reduced where it offers F service.

Check-in - I like the F check-in based on my status - again I dont think the other alliances offer this if you are not flying F

New Members - I think it is great JL is joining - RJ really doesnt help as they dont hub in the Middle East so to speak - it would be nice if Oneworld can attract a quality ME member such as Emirates, Qatar or Etihad - although even GF would be ok.

Hope this helps!