online.net is better to be honest
Online.net only uses branded hardware and server hardware (except the 'SC' product range) : Xeon, ECC, Hardware RAID, ...
I'd say the price/quality ratio is better at Online.net but you just might not need that higher quality if you are running a personnal blog.
Speaking about the support, OVH has been internationnaly selling for much longer than Online.net, it's still quite 'fresh' at Online.net.
About the network, OVH's one is wider and it has a datacenter in Canada, Online.net only has datacenters in France and their network has gone international last summer with many peerings/transits (they used to rely on a French ISP before). Online.net servers are all gigabit connected. Both network are DDoS protected. OVH has a mandatory SMTP filter which has its pros and cons.
Twice (in different context) I have tried to use online.net and fallback to OVH/Kimsufi. Why ? First time unability for them to sell servers, second time unability for them to get paid.