Main thing to look for is the way they setup their network.
You can find a provider who has 2 very expensive providers and 1 cheap one but sends a lot of traffic out cheapest one (forced).
You can find providers that do equal path bgp between all upstream providers.
You can find providers that optimize their routes, automatic or manual.
Some providers peer directly with others to reduce costs.
Some do it to improve network performance.
It is important to find out what the host claims and MORE important to verify it.
I have seen with low commit levels $2 to $25+
In most cases you get what you pay for. In some cases its marketing BS.
Ask why their bandwidth is better and verify it.
I used to be with a host many many years ago who claimed the world but their network was crap, internal and the way they setup their upstreams.
So in addition to their upstream and peers watch for internal network setup.
Are switches congested (usually called shared but some host claim dedicated) where you can not use full bandwidth allocated for example.
24port switch with 100mbps uplink to router was what this (crap) host offered me 10mbps Un-metered servers on.
Note if all clients use 50% of bandwidth that exceeds the uplink.
They had a lot of issues so you would see that often, since they were cheap a lot of boxes were not exactly Important to their owner left unattended, all of a sudden all servers would do 10mbps on same switch. Their own website was up, I was down.
When sql slammer hit, downtime was a regular event. Again their site was up, I was down.
Also make sure you are on your own vlan and subnet.
check to see if they are able to stay up if multiple providers fail.
for example in my situation Los Angeles I made sure my host was not establishing connection in 1 building. That would mean if connection to that building was lost or that building had issues with power the provider would be down no matter how many lines they had.
Also make sure they are able to stay online in case of multiple upstream downtime. Some say they are redundant but having 4 GIGE uplinks when you have 2.1Gbps of traffic at peak time is not what I would consider good. You are just betting you do not lose 2 providers during peak hours
I saw one provider tell my client they are redundant since they only utilize 20% of their network.
It was a new host apparently in MO, they had gotten 1 GIGE link cheap but their redundancy was 2x FE lines.
1xGIGE and 2xFE and you use 250mbps is not redundant enough for me.
It is true that bandwidth prices are lower now, it is also (IMO) true that a lot of crap is being passed as good.
If you see something that is too good to be true, it more than likely is. Just the cost of equipment to provide good network is more than some prices I have seen.
On the flip side, does it really matter. Do you really care to pay premium. In some cases it does not really matter anyway.
I know for SEO uptime matters, for video and voice latency and jitter but if you are running file server (backup) do you care if your server is down 1Hour?
There are handful of providers I really like, 3 of them are big providers. So size also does not matter.
So it all depends on what you need and who best matches your needs.
Price should be a concern but not the only concern.