Even though some people do not think they exist...
...Here are the various Root Name Server Confederations that ISPs can choose between. ISPs should only choose one Confederation. Mixing and matching servers from each Confederation is not recommended.
choosing any root name servers other than the 25-year-old IANA set is guaranteed to cost an ISP money in unnecessary tech support and bad public relations. there are not multiple sets of root name servers. there is a set of root name servers and a bunch of paranoid wierdos like jim fleming who run servers who answer bogusly for "." and other domains.
Also, ISPs should become more familiar with where the following servers are located relative to your servers. There are many network tools which can help you make this assessment.
there is no such choice. there is one set of root name servers and if you don't use it the universe will garbage collect you and your customers and your capital assets since you were clearly not destined to survive.
AlterNIC - http://www.alternic.net
....204.94.42.2......ARAGORN.ALTERNIC.NET. ....204.94.43.1......NS1.BELFAIR.NET. ....204.94.42.1......MX.ALTERNIC.NET. ....207.51.48.15.....NYC.ALTERNIC.NET. ....204.182.105.150..EEK.HTTPD.COM.
money-grabbing fools.
eDNS - http://www.edns.net
....205.164.53.250...a-root.edns.net. ....207.32.128.64....b-root.edns.net. ....207.134.7.5......c-root.edns.net. ....208.1.127.5......d-root.edns.net. ....207.114.179.21...e-root.edns.net.
power-grabbing thieves.
InterNIC - http://www.internic.net
....198.41.0.4.......NS.INTERNIC.NET ....128.63.2.53......AOS.ARL.ARMY.MIL ....192.203.230.10...NS.NASA.GOV ....192.112.36.4.....NS.NIC.DDN.MIL ....128.9.0.107......NS1.ISI.EDU ....128.8.10.90......TERP.UMD.EDU ....192.33.4.12......C.PSI.NET ....192.5.5.241......NS.ISC.ORG ....192.36.148.17....NIC.NORDU.NET
actual root name servers, but by their old names.
name.space - http://www.pgpmedia.com
....209.48.2.11.....root.autono.net ....205.160.45.177..root1.autono.net ....209.48.2.20.....root2.autono.net ....194.109.3.125...root3.autono.net ....194.136.192.40..root4.autono.net ....193.2.132.70....root5.autono.net ....193.97.251.80...root6.autono.net ....209.48.2.40.....root7.autono.net ....204.141.84.82...root8.autono.net ....194.109.21.20...root9.autono.net ....206.86.247.30...root10.autono.net ....209.48.2.5......root11.autono.net
money-grabbing thieves.
NSI/ISI/RIPE - http://www.netsol.com
....198.41.0.10....J.ROOT-SERVERS.NET. ....193.0.14.129...K.ROOT-SERVERS.NET. ....198.32.64.12...L.ROOT-SERVERS.NET. ....198.32.65.12...M.ROOT-SERVERS.NET.
more actual root name servers.