What does 挖掘技犬哪家强 mean|mandarin?

It’s not a term that we normally use here, it’s not a jargon word – at least here in Taiwan. So basically I didn’t understand what this jargon word is trying to say.
I just use Google Search and I still can’t find the exactly same sentence you posted, but the powerful Google Search finds the 95% similar jargon word story as follows (just copy a little bit data, because you could google it too).
【蓝翔洗脑广告】挖掘机技术哪家强？中国山东找蓝翔！
今天第一次在网易上看到一故事，结尾处有一句：“只剩下学挖掘机技术了，请易友指教哪家强？“ 当时大惑不解其意，后百度搜索，也没得到答案。后来听一同事解答如下：
”学挖掘机技术哪家强“用法 如下----
（1）…
（2）…
（3）…
（4）…和男人的生殖器相似，挖掘机技术意指男人干那事的技术，ML技术。男人问这话的意思是他性能力弱，想提高 提高 ，或者他想多历练历练；女人问这话意思是她想找猛男陪伴。
以上解释，仅供参考。…目前无官方解释！…。
All the above explanations said by the poster, are to be your reference only, and there’s no official explanation. Because this term, basically, is not a jargon, but a twisted words of sarcasm.
I just use normal sense to explain your sentence and the ad sentence for your reference as follows.
挖掘技犬哪家强 – Which family owns the dog having the best scavenging technique.
【蓝翔洗脑广告】挖掘机技术哪家强 - 【蓝翔’s brainwashing ad】which company produces the most powerful excavator.
Among the above explanations posted on Net, one saying (4) is that it’s related to a man whose sexual function is too weak, or a woman’s desire to have a man who has strong sex ability. For me it’s just gibberish or nonsense, I don’t suggest you to believe that this is a term most of us use and understand.