Despite the comstant cintracting of SH players how good is the NH club rugby

I raised the above question in view of the last three victories of the Cheetahs in the Pro 14.   We know that Zebre is a poor side and that victory must for all intents and purposes be disregarded.
However, the victories in the Leinster and Osprey games and the margins of the two victories makes me really wonder about the strength of European Club rugby - especially since the two clubs  are also participants in the European Championship Cup and especially Leinster has a good record in that competition,  
Against that must be borne in mind that the Cheetahs was one of the bottom franchises in Super Rugby accounting for the Cheetahs to be dropped from that competition.   One can only wonder what will happen if the Pro14 teams really come up against top SH teams playing in Super Rugby.
One must further bear in mind that the Pro14 is made up of the top clubs in Ireland, Scotland, Wales and Italy.   This raises another question about the strength of their international sides  and the problem records of the Springboks against those international teams.  
Is it because of some serious problems plaguing SA rugby like race-based selections and serious coaching deficiencies?  

 ...don't think there's much difference between NH and SH rugby is there?...there's strong teams and weaker teams in every competition... but Ulster and Scarlets are the Pro 14 teams to beat by the looks...Glasgow under Dave Rennie also looking strong...
If the Cheetahs can win at home against Glasgow next week that will be a major achievement as Glasgow are undefeated and leading Conference A..
In the Aviva Premiership Saracens and Exeter look the strongest for mine but they're all much of a muchness. Hard to seperate the top five or six French clubs in the Top 14 as well so the Europeans Champions Cup could be anybodys for the taking..Saracens would have to be strong favourites though...
Talking about the European Champions Cup, is any one starting a league for the forum?