Hi there,
The answer is: it depends. Many factors will determine was is best for each individual investor. For example, if you are at or near retirement, preserving capital and a strong dividend yield may be a priority. This means, one with a higher yield and lower growth would be preferable. If an investor has a longer investment horizon than perhaps on that carries a little bit more risk with a higher growth rate and lower yield would make sense. Furthermore, the makeup of your portfolio will also impact your decision. Using your example, if you already have high exposure to pipelines - then ATD.B may be the better choice in the name of diversification.
Bottom line, investors need to do what works best for them. There is simply no cookie-cutter approach. For me personally, I have a mix of these and eventually I can see my self rotation out of some of the lower yield companies into higher (but stable) yielders. If this was me and I was just starting out - I'd likely focus on building a position in ATD.B first.
Worth noting, one of the mistakes dividend growth investors make is to ignore those with low yields and higher dividend growth rates - at least in my opinion. I've seen it often where DGIs ignore anything with low yields. To me, that is a mistake and ignoring total returns will lead to underperformance. The second mistake DGIs make is to get emotionally attached to their stocks. Just because a company has a long history of dividend growth, it doesn't mean that the streak will continue if fundamentals deteriorate. In recent years, we've seen staunch defenders of former Aristocrats like CJR.B and HLF cut the dividend because their high yields simply could not be sustained. Yet, for anyone not invested in the company or chasing yield, it was clear that dividend cuts were on the way - the fundamentals simply did not support a dividend. The single biggest reason why retail investors underperforms is because they let emotions win over decision making. Let the numbers do the talking.
I know this doesn't outright answer your question, because there is no right answer here. You ask 10 different dividend growth investors, they will likely give you 10 different answers. I think in principle however, it'll depend mainly on your investment timeframe, risk tolerance and diversification. Just don't approach it from an all-or-nothing perspective - each of them deserve consideration by DGIs.
Mat