There might be some 1st Gen Helos 6-24's out there still for sale, it has a 30mm tube, these are ok but not up to the quality of the G2 Helos scopes. The Helos G2 6-24 is awesome for the money!!! Be aware that it has a 34mm tube and is on the heavy side so it might not be for you if you plan on walking around a lot with your rifle.
The Midas TAC series are even higher quality than the Helos line and they are hard to beat but don't have illumination and IMHO these are basically an ETR quality scope lacking illume.
Both the Helos G2 and the Midas TAC are so good its hard for me to make up my mind which one I like more - only because the Helos G2 has illume and locking turrets as well as focusing down to 10Y. The 5-25 TAC only goes down to 25Y but one can still go to lower magnification to clear up the image at around 15-20Y. The 5-25 has a 34mm tube so its a bit heavy. The TAC series wins in the glass department.
Haven't been behind the Helix yet so i can't make a fair judgement.